docs: def do(self, func, *args, **kwargs):
          """Apply the function to myself, and return myself.
  
          Look up the function in the database if needed. Pass it any
          arguments given, keyword or positional.
  
          Useful chiefly when chaining.
  
          """
          if not callable(func):
              func = getattr(self.engine.function, func)
          func(self, *args, **kwargs)
          return self